CCL17 and neoplasm: Recent studies have shown that tumor cells can recruit Treg cells to exert immunosuppressive effects and promote tumor progression by secreting certain cytokines, such as CCL17 and CCL20.[8, 9] Notably, with the emergence of single‐cell RNA sequencing (scRNA‐seq) technology, it has become increasingly recognized that Treg cells exhibit heterogeneity in the tumor environment.